Gallery Model with Picture and Comments in MVC3

Question

I've just learnt how to upload pictures and bring them in view Model.

Now I'm trying to Add comments to the pictures. That means a picture can have more comments. So I created 2 Tables, called "Gallery" and "Comment". They are related by 'One to Many'.. My model looks like that..


public class GalleryEntries
    {
        public List Entries { get; set; }
    }

    public class GalleryEntry
    {
        public Gallery GalleryImage { get; set; }
        public List Comments { get; set; }
    }

And the controller looks so..


GalleryDataContext GalleryDB = new GalleryDataContext();

        public ActionResult Index()
        {
            GalleryEntries model = new GalleryEntries();
            GalleryEntries galleryentries = new GalleryEntries();

            foreach (Gallery gallery in GalleryDB.Galleries)
            {
                GalleryEntry galleryentry = new GalleryEntry();
                galleryentry.Comments = GalleryDB.Comments.Where(c => c.BildID == gallery.ImageID).ToList();
                galleryentry.GalleryImage = gallery;
                galleryentries.Entries.Add(galleryentry);
            }

            return View(model);
        }

But it doesn't work. :( It displays "Object reference not set to an instance of an object" at the line where

 "galleryentries.Entries.Add(galleryentry)

stands.. How can I solve this problem?

Peter Peter · Accepted Answer · 2011-12-09T23:36:42

I think the problem is that you don't initialize the GalleryEntries.Entries property anywhere ... so you're attempting to add galleryentry to a List that does not exist yet, hence the NullReferenceException.

You could initialize Entries in the constructor:

public class GalleryEntries
{
    public IList<GalleryEntry> Entries { get; set; }

    public GalleryEntries() {
        Entries = new List<GalleryEntry>();
    }
}

Gallery Model with Picture and Comments in MVC3

1 Answers